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Old December 4, 2013, 06:37 PM   #1
RX-79G
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Reading mentions of IPSC Power Factor recently got me interested in the math behind this calculation. A ball of lead a little over an inch in diameter thrown at 60 mph (12 year old Little League pitcher) makes Major, like .45 ACP.

Would it be fair to say that if I threw a lead ball lighter than a baseball it would do all the damage of a .45, and more than 9mm, according to the IPSC system?
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Old December 4, 2013, 08:24 PM   #2
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My cabbage and melons are lethal then!!
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Old December 4, 2013, 09:25 PM   #3
saleen322
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Good points. People have to remember that these numbers are guidelines for games and not based on actual energy. More over, think how many times someone will say that heavier bullets at the same power factor are less snappy. Well since energy rises at the square of velocity while power factor is just a product of mass times velocity, the heavier round at the same power factor has less kinetic energy so that is why it kicks less.
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Old December 5, 2013, 09:11 AM   #4
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The power factor is a system designed to favor the 45acp.
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Old December 5, 2013, 09:32 AM   #5
Brian Pfleuger
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Quote:
Originally Posted by saleen322 View Post
Good points. People have to remember that these numbers are guidelines for games and not based on actual energy. More over, think how many times someone will say that heavier bullets at the same power factor are less snappy. Well since energy rises at the square of velocity while power factor is just a product of mass times velocity, the heavier round at the same power factor has less kinetic energy so that is why it kicks less.
Except that recoil is based on momentum, not kinetic energy.



To the original point, Power Factor is for a game. It has no real life implication/application.
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Old December 5, 2013, 09:37 AM   #6
MrBorland
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Quote:
I threw a lead ball lighter than a baseball it would do all the damage of a .45, and more than 9mm, according to the IPSC system?
Despite it's name, "Power" Factor (mass x velocity) is a measure of momentum, not power or energy, and these latter elements are what do damage: Momentum's good for moving things but not damaging them.

The 1" lead ball thrown at 60 mpg may have the same PF & momentum as a .45acp round, but it's only got about a tenth of the energy. Combined with it's abysmal sectional density, it'll do little damage, relative to a .45acp round.
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Old December 5, 2013, 10:35 AM   #7
g.willikers
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Just a guess, but
The power factors might exist to level the playing field as regard to recoil, and how fast one can shoot the targets.
Especially since the scoring systems are so connected to timed speed and rate of fire.
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Old December 5, 2013, 11:25 AM   #8
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Why guess? That was the purpose of power factoring.
It came about when cheap chronographs became available and building and operating the ballistic pendulum was unnecessary.
There were other measures. I recall one that had a complicated formula covering both momentum and energy. You would be well rewarded for shooting a Magnum if that system was used in scoring.

This thread shows the problems that can arise from extrapolating a value beyond the range it was defined for. Kind of like using Taylor Knock Out for pistols and varmint rifles.
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